1-Methyl-4-nitro piperazine-d11 is the deuterium labeled 1-Methyl-4-nitro piperazine. 1-Methyl-4-nitrosopiperazine (MNP, MeNP,N-Methyl-N-nitrosopiperazine) is a potential impurity in sartans, non-steroidal anti-inflammatory drugs (NSAIDs), and thiazide diuretics[1].